Conventionally, fabrics woven by the warp and weft have been widely used for cylindrical fabrics and, particularly in the paper-manufacturing processes, have been employed for a cylinder fabric of a cylinder machine, a dandy roll, a paper-manufacturing cylinder mold, a dehydrating filter cloth, and the like. In the field of paper manufacturing, it has been one of objects to improve the texture pattern or the quality of paper upon making paper. A cylindrical fabric is used by being mounted on or covering a cylindrical machine casing in a tightened state and, in the paper-manufacturing processes, is required to have an excellent surface property so as not to transfer mesh marks, joint marks, or the like of the fabric onto paper, to improve the yield of paper manufacturing, to be excellent in water filtering property, fiber supportability, wear and abrasion resistance, dimensional stability, and running stability, to be easily mounted, and so forth.
By explaining cylindrical fabrics for use in paper manufacturing wherein the requirements are strict among those to cylindrical endless fabrics as described above, it is possible to understand most requirements to the cylindrical fabrics and solutions thereof. Therefore, the present invention will be described hereinbelow taking the cylindrical fabrics for paper making as an example.
As cylindrical fabrics called cylinder molds, there are available fabrics made of plastics and fabrics made of metal. The cylindrical fabric is used by being mounted on or covering a cylindrical machine casing in an adhering state. For mounting the plastic fabric, such a method has been often used wherein a fabric formed into a cylindrical shape in advance by a known joining method is placed on an object cylinder so as to cover it, then adhered to the cylinder by thermosetting with steam or the like. Therefore, yarns forming the fabric are made of a material having a relatively high heat contraction coefficient. On the other hand, in case of the metal fabric, such a method has been mainly used wherein a non-endless fabric is cut into a parallelogram having parallel opposite sides and crossing angles of the sides being other than a right angle, and the two opposite sides are butted to each other and joined together to thereby form the fabric into a cylindrical shape. As prior art, Japanese Examined Patent Publication No. S45-17363 (1970) (hereinafter referred to as “JP-B-S45-17363”) describes that one angle of a parallelogram is set to 25° to 65°, particularly 45°. When the fabric is joined according to such a method, a joining portion is inclined relative to an axis of the cylinder or the cylindrical fabric, and therefore, the fabric can be mounted in an adhering state by tightening it in the axial direction of the cylinder or the cylindrical fabric. There is also a merit that transfer of joint marks onto paper is relaxed by inclining the joining portion.
As shown in the drawings of JP-B-S45-17363, the plain weave pattern is popular among weave patterns. With respect to the plain weave pattern, there has been a drawback that although the number of intersecting points between the warp and weft is large, inasmuch as meshes of a fabric are oblique, fibers extending in the warp direction are liable to come off the meshes so that sufficient fiber supportability can not be obtained. Further, there has also been a problem that if the number of yarns is increased for improving the fiber supportability, ventilation is degraded to thereby lower a dehydrating capability. Moreover, if the joining portion is inclined at 25° or more relative to the axis as in the prior art, joint marks of the joining portion become more inconspicuous, however, an acute angle of a parallelogram for forming a cylindrical fabric becomes small and, following it, a net having a large area is required, portions to be discarded increase, and a length of the joining portion is prolonged. Therefore, there has been a problem in terms of cost, labor, and the discarding amount.